Platform movement detection latencies in young adults, elders with peripheral neuropathy and non-diabetic elders

The effects of acceleration, displacement, neurological status and age on movement detection latency were studied in three groups - 11 young adults, 7 neurologically intact elder adults, and 7 elders with (diabetic) peripheral neuropathy. Acceleration detection thresholds for anterior perturbations of 1, 4, and 16 mm of the surface where the subjects stood was previously determined for each subject via a 2-alternative-forced-choice protocol, with longer moves yielding lower 2AFC thresholds that varied by group. Using the threshold value for acceleration from the 2AFC method, and 125% of that threshold, latencies from the start of a platform move to movement detection were determined for all 3 displacements. Latencies and percent-correct detections were compared among groups. Lower acceleration values (over longer moves) required longer latencies for motion detection. While no significant differences among groups existed in latencies at 100 or 125% of threshold, a group difference in latency was seen to a super-maximal acceleration (>500% of threshold). The percent-correct detections showed that latency testing was a less sensitive indicator of acceleration thresholds that those determined by the 2AFC test. These results are discussed with reference to the psychometric (ROC) curve.